The Autodiscover service makes it easier to set up Outlook and mobile phones. The Autodiscover service uses a user's email address and password to automatically set up a user's profile.
To troubleshoot this issue further, run the Exchange ActiveSync Autodiscover test in Microsoft Remote Connectivity Analyzer. If the user is using a local wireless network to connect to Exchange Online, the user should run both tests to make sure that the local network allows for connections to the ActiveSync endpoints.
Test Exchange Online ActiveSync access externally by using Remote Connectivity Analyzer
Note Admins may want to guide users through running Remove Connectivity Analyzer if this is necessary. The Exchange ActiveSync Autodiscover test requires the user to enter his or her credentials.
In a web browser, browse to the Microsoft Remote Connectivity Analyzer tool at the following website:
If you have an Exchange hybrid deployment, set up the Autodiscover public DNS records for your existing SMTP domains to point to an on-premises Exchange server. For more information, see Hybrid deployment prerequisites.
We recommend that you use Autodiscover when you try to set up mobile devices. However, if you want to set up a mobile device without using Autodiscover, use the procedure that is described on one of the following Microsoft websites:
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